This research investigates the concurrent, short-term, and long- term effects of nutritional intervention in the preschool years on bone growth and mineralization. This study will investigate the impact of a well-controlled nutritional supplementation project in Gautemala on measures of bone metabolism, bone sizes, and bone mineralization in young children, and in the same individuals when adolescents and young adults. Measures of bone metabolism are based on single blood samples. Measures of bone size are made directly from radiographs of the hand and wrist, and indirectly from gross body measurements. Bone mineral content is determined via single-photon absortionmetry, based on a low-energy radiation source. Adolescence and young adulthood are critical periods in the development of adult bone mass. The study will also describe the patterns of age-associated bone mineral loss in adult Guatemalan women. Data for children participating in the longitudinal study of the Institute of Nutrition of Central America and Panama, carried out from 1969-1977, will be analyzed. This original study investigated the effects of providing two different nutritional supplements to four test communities. Additionally, data on bone growth, metabolism, and mineralization will be obtained from these same individuals as adolescents and young adults, and from individuals of corresponding ages in two control communities. These data will be combined with data on many other aspects of growth, physical performance, and psychosocial development being collected in a currently funded "Parent" project. Together the data will be analyzed to answer important questions concerning the permanency of nutritional intervention early in life. In addition, important research questions relating early childhood growth and nutritional factors to later bone health will be addressed.